Arc chute with trap for products of arcing



DeC- 23 1952 D. E. wEsToN ARC CHUTE WITH TRAP FOR PRODUCTS oF ARCINQFiled Aug. 5, 195o /Arfvrrndrdva the zione of arc initiation.

Patented Dec. 23, 1952 ARO CHUTE WITH TRAP FOR PRODUCTS OF ARCING DonaldE. Weston, Wauwatosa, Wis., assignor to Allis-Chalmers ManufacturingCompany, Milwaukee, Wis.

Application August 5, 1950, Serial No. 177,938

8 Claims.

, This invention relates to circuit interruptingv devices and moreparticularly to -circuit breakers a magnetic blowout coil or an airblast, into an arc chute which is arranged to quench the arc bylengthening it, cooling it, or a combination of both.

The interruption of large current power arcs is often accompanied by theemission of a great deal of are products including incandescent metalparticles or other inorganic substances. These particles, if not conned,tend to break down the dielectric strength of the surrounding air andthereby increase the time necessary to extinguish the arc, or causefailure of the circuit breaker.

In accordance with the invention claimed a new andimproved circuitinterrupting device is provided comprising relatively movable contactswhich are actuated to initiate and elongate Aan arc therebetween. Thearc as it is elongated is transferred from the zone of arc initiation toan arc chute zone suitable for arc extinguish- -m'ent. The arc chute isarranged to receive the arc at one end thereof and exhaust the hot gasesat the other end thereof. A perforated insulating plate is arranged atleast partly within the arc receiving end of thel arc chute adjacent thezone of-arc initiation to provide with an element of-the arc chute apassage communicating with a zone or region in the arc chute remote fromThe perforated insulating plate intercepts the products of arcingissuing from the zone of arc initiation, cools and deionizes the aircarrying the products of arcing, and vents it to :another zone of thearc chute through the passage formed by the perforated insulating plateand the element of the arc chute.

It is, therefore, one object of the present invention to provide a newand improved arc inter- -rupting device in which the products of arcingare isolated from the arc stream to rapidly restore the dielectricstrength of the air surrounding the arcing contacts.

Another object of the present invention is to provide a new and improvedarc interrupting device in which the products of arcing are trappedimmediately adjacent the region of arc initiation.

A further object of the present invention is to trap the metal vaporsnear the region of arc initiation, cool and deionize the surroundingair, and vent it back into the air stream at a point downstream of theregion of arc initiation.

Objects and .advantages other than those above set forth will beapparent from the following description when read in connection with theaccompanying drawing, in which:

Fig. 1 is a view in vertical cross section of a magnetic blowout typecircuit breaker employing the present invention;

Fig. 2 is an enlarged view in horizontal cross section of a portion ofthe embodiment illustrated in Fig. 1 taken along the line II-II;

Fig. 3 is a view in vertical cross section taken along the line III- IIIin Fig. 2; and;

Fig. e is a view in transverse cross section taken along the line IV-IVin Fig. 3.

Referring more particularly to the drawings by characters of reference,Fig. 1 illustrates a magnetic blowout type of circuit breaker includingas elements thereof a pair of terminal studs 6 and l for connecting thecircuit breaker to line conductors (not shown). Although in general,circuit breakers of the type considered in Figs. 1 to 4 are providedwith a plurality of similar pole structures, one for each phase of apolypliase electric circuit, only one such pole structure is shown inthe drawings and the circuit breaker will be described in detail as ifit was of the single pole type.

The circuit interrupter or breaker in Fig. 1 comprises essentially meansfor opening the circuit to form the interrupting arc and an arcextinguishing structure. Specifically, the circuit opening meanscomprises a fixed current carrying contact 8, a tertiary contact 9, afixed arcing contact IU, and a movable arcing contact II. Arcing contactI I is mounted on a lever 28 which is pivctally mounted at I2 on anextension I3 of the circuit breaker stud 6 and is operated by means of.a reciprocally movable rod I4. The operating rod I4 is suitablyconnected to an actuating mechanism (not shown) for operating themovable contact between closed and open circuit positions. Fig. 1illustrates the movable contact il in closed position. The arcingcontacts are electrically -connected to the lower ends of terminal studs6 and '1. Accordingly, when the reaker is connected in series in a powercircuit and the arcing contacts are separated, an arc may be initiatedacross the gap formed between the contacts. y

For the purpose of interrupting this power arc, an arc extinguishingstructure, such as an arc chute it, may be mounted so as to receive thepower are which is under the influence of the magnetic blowout means.The arc chute preferably is disposcd directly about and above the arcingcontacts, as shown, when the blowout means act upward, but may bemounted in any other suitable location when the blowout means act inother directions. The switch or arcing contacts and the magnetic blowoutstructure can assume any preferred form so that a brief descriptionthereof will be sumcient. The magnetic blowout may comprise a core Il,poles I8, and a coil It which is electrically connected to the terminalstud 'I and to a metallic are runner I3 so that the arc current (as thearc travels along the runner) flows through ther blowout coil in amanner well known in the art.

Normally the current is carried in the closed circuit position of thebreaker by the spring biased contact 8. As the movable arcing Contact II is actuated to open circuit position, current is shunted from xedcontact 8 first to fixed contact 3 and afterwards to fixed arcingcontact Ill. As the arc is drawn by the movable arcing contact II, thearc terminal of arcing contact I is transferred to arc runner I3, whichis usually an extension arm of the fixed arcing contact I0. As themovable arcing contact II approaches or reaches its full opening strokethe arc terminal transfers from the movable arcing contact II to an arcrunner 25 which directs the arc in the arc chute I5. The arcing contactI0 and the arc runner I9 are electrically connected in series with theblowout coil I and stud i. Accordingly, the

blowout coil is already energized at the inception :i

of the arc to influence the arc in a well known manner, i. e. to driveit in the arc chute I5 in an expanding loop. It will be apparent to oneskilled in the art that the blowout field can be utilized in the mostefiicient manner by disposing the iron poles I8 so as to cooperate withthe blowout coil in the conventional manner outside ofthe arc chute.

In accordance with the invention a pair of insulating perforated plates23 (clearly illustrated on an enlarged scale in Figs. 2 to 4) arearranged to extend within the arc receiving end of chute I5 to capturethe incandescent particles emitted in the Zone of arc initiation. Eachperforated plate 23, which may be made of a ceramic material, is spaceda suitable distance apart from a different one of a pair of insulatingmembers 2| and 22 by spacers 3 I. Insulating members 2| and 22 in turnare secured to support members 21 and 23, which are mounted adjacentside walls 25 and 26 defining arc chute I5. Perforated plates 23 andinsulating members 2| and 22 provide a pair of passages 30. Passages 35are provided for bypassing air largely stripped of are products aroundat least the zone of arc initiation. Plates 23 are arrangedsubstantially parallel to the path of' contact movement and on oppositesides of the arcing contacts.

The majority of the perforations of plates 23 are concentrated near tothe stationary arcing contact I0 for providing not only rapid venting ofthe arcing Zone at the time of initial contact separation but, inaddition, effective deionization of the vented air by surface action ofthe perforations. countersunk on the side of the plate nearest thearcing contacts to further increase the total surface area exposed tothe air for deionization purposes.

End sections 32 and 34 of perforated plates 23 Each perforation or hole24 may be are spaced from arc runners I3 and 20 and arrangedsubstantially coextensive with sections thereof for providing apredetermined path along the arc runners for the movement of the arc.

Perforated plates 23 thus provide passages 30 which are each completelyopen on its top, bottom and sides. Immediately above the perforatedplates 23 and Within the exhaust zone of chute I5 is mounted a pluralityof barrier structures 33 which further elongate and cool the arc if itis not extinguished before reaching that point.

Under normal interrupting conditions an arc is initiated immediatelyupon separation of the arcing contacts` I0 and II. The terminal of thearc on fixed arcing contact IU is driven over arc runner I3 toward theexhaust end of arc chute I5 by the magnetic blowout means and thethermal effect of the arc. As movable arcing contact I I nears its fullyopen position the other terminal of the arc jumps from Contact I to arcrunner 20 and is also driven by the blowout` means and the thermaleffect of the arc toward the exhaust end of arc chute I5.

Upon initiation of the arc and also during its movement along the arcrunners I 9 and 20, emission of arc products including incandescentmetal particles or other inorganic substances occurs which heretoforewere jetted into the area surrounding the elongated arc. Theseincandescent particles reduce the -dielectric strength of the air orother gas surrounding thearc, thereby increasing the possibility ofelectric breakdown of the circuit breaker or at least restriking of thearc after it was extinguished.

The new and improved trap passages formed by perforated plates 23 andmembers 2|, 22 of arc chute I5, however, reduce the freeow of thearcproducts from their source, namely the arc terminals, toward the zoneor region occupied by the elongated arc. As the power current iiowsthrough the arc, the arc productsare emitted in all directions from theareas occupied by the arc as it moves from the arcing contacts and alongthe arc runners. By arranging the perforated plates immediately adjacentthe zone of arc'initiation in the manner described, the arc products areconfined, cooled and conveyed by plates 23 into passages 3Il. In suchpassages thearc productsv are trapped and separated from the hot ionizedair displayed by the occurrence ofthe arc. The air is cooled anddeionized byplates 23 and is directed through passages 30 toward a space35 confined between barrier structures 33, which forms a part of theexhaust zone ofthe chute. In space 35 the cooled' air is mixed by thegases surrounding the` arc to help to cool and deionize the arc zone.The dielectric strength of the gases surrounding' the contactstructureis restored, thus preventing breakdown of the gap in thecontact region because of reionization of the zone of arc initiation byarc products.

Although but one embodiment of the present invention has beenillustrated and described, it will be apparent to those skilled in theart that various changes and modifications may be made therein withoutdeparting from the spirit of the invention or from the scope of theappended claims.

It is claimed and desired to Patent:

l. [in electric circuit interrupter comprising a pair of relativelymovable cooperating :arcing contacts, means for separating saidc-ontactsto initiate 'and elongate an -arc therebetween, and an arcchute for receiving the arc at oneend secure by Letters thereofandexhausting the hot gases at the other end thereof, said arc beingdrawn 'by said contacts transversely of the longitudinal axis of saidchute, said chute comprising means for trapping products of arcing fromthe ,zone of arc initiation and venting air stripped of said products ofvarcing to a different zone within said chute remote 4from said zone oflarc initiation.

2. An electric circuit interrupter comprising a pair of relativelymovable cooperating arcing contacts, means for separating s-aid contactsto initiate and elongate an ar-c therebetween, and an arc chute forreceiving the arc at one end thereof and exhausting the hot gases at theother end thereof, said chute comprising a perforated insulating platemounted within the arc receiving end of said chute adjacent the zone ofarc initiation for dividing the arc receiving end of said chute into anarc conducting passage and la tributary passage for receiving theproducts of arcing, said tributary passage being arranged to trap theproducts of -arcing and to vent gases stripped of said products ofarc-ing back into said arc conducting passage at -a point near theexhaust zone of sai-d chute.

3. An electric circuit interrupter comprising a pair of relativelymovable -cooperating arcing contacts, means for separating said contactsto initiate and elongate an arc therebetween, and an arc chute forreceiving the arc at one end thereof and exhausting the hot gases at theother end thereof, said arc being drawn by said contacts transversely ofthe longitudinal axis of said chute, said chute comprising a perforatedceram-ic plate mounted within the arc receiving end 'of said chute nearthe zone of arc initiation and extending longitudinal to the directionof relative movement of said contacts for dividing the arc receiving endof said chute into an arc conducting pas- Sage Iand a tributary passagefor receiving the products of arcing, said plate effectively deionizingthe products of arcing and providing a means for venting through saidtributary passage the gases stripped of said products of ar-cing backinto said arc conducting passage at a point near the exhaust zone ofsaid chute.

4. An electric circuit interrupter comprising a pair of relativelymovable cooperating arcing contacts, means for separating said contactsto initiate and elongate an ar-c therebetween, and an `arc chute forreceiving the arc at one end thereof Iand exhausting the hot gases atthe other end, said chute comprising a pair of side walls and a pair ofperforated ceramic plates mounted Within the arc receiving end, saidplates extending on opposite sides of the path Vof contact movement andsubstantially parallel thereto to form between said plates an arcconducting passage, said plates forming within the said side walls ofsaid chute la pair of auxiliary passages for bypassing at least the zoneof larc initiation and merging With said arc conducting passage in theexhaust zone of said chute, the perforations of said plates being:arranged to trap, cool and convey the products of arcing from the zoneof arc initiation into said auxiliary passages.

5. An electric circuit interrupter comprising a pair of relativelymovable cooperating arcing lcontacts, means for separating said contactsto initiate and elogate an arc therebetween, ya pair of side wallsdefining an arc chute for receiving the arc at one end thereof andexhausting the hot gases at the other end, arc runners for aiding themovement of said arc in said chute, magnetic blowout means' for driving.the are in-saidchute toward the exhaust endthereof, and trap meanscomprising a pair of insulating perforated plates mounted to extendwithin said chute, said plates 'being arranged on opposite sides of thepath of -.said arc conducting passing in the exhaust zone of said chute,the perforations of 'said plates being arranged to cool and convey theproducts of varcing from the zone of arc initiation to said lauxiliarypassages, said plates comprising end sections which are arrangedsubstantially coextensive with sections of s-aid arc runners forproviding predetermined paths along said arc xrunners for movement ofthe arc.

6. An electric circuit interrupter comprising a pair of relativelymovable cooperating arcing contacts, means for separating said contactsto initiate and elongate an arc therebetween, and an arc chute forreceiving the arc at one end thereof and exhausting the hot gases at theother end thereof, said chute comprising means for dividing the arcreceiving end of said chute into an arc conducting passage and anauxiliary passage for receiving the products of arcing, said dividingmeans 'being provided with a plurality of perforations near the zone ofarc initiation for venting the products of arcing from said zone intosaid auxiliary passage, said auxiliary passage venting said gasesstripped of said `arcing products back into said arc conducting passagein another zone within said chute remote from said zone of arcinitiation.

7. An electric circuit interrupter comprising a pair of relativelymovable cooperating arcing contacts, means for separating said contactsto initiate and elongate an arc therebetween, and an arc chute forreceiving the arc at one end thereof and exhausting the hot gases at theother end thereof, said chute comprising a perforated insulating pla-temounted within the arc receiving end of said chute near the zone of arcinitiation and extending substantially longitudinally of the directionof relative movement of the arcing contacts for providing an arcconducting passage and an auxiliary passage bypassing at least said zoneof arc initiation and merging with said arc conducting passage in theexhaust rone of said chute.

` the perforations of :said plate being arranged to trap, cool andconvey the products of arcing to lsaid auxiliary passage, said auxiliarypassage venting said gases stripped of said arcing products into saidarc conducting passage at a point remote from the zone of arcinitiation.

8. An electric circuit interrupter comprising a pair of relativelymovable cooperating arcing contacts, means for separating said contactsto initiate and elongate an arc therebetween, a pair of :side wallsdefining an are chute for receiving the plates, being arranged to trap,cool and convey UNITED STATES PATENTS.

the productsA of arcing from the zone of are ini- Number Name Datetiation to said auxiliary passage, said auxiliary 1 944 403V l Chamv Jan23 1934 passage venting said gases strippedof said arcing 234537'5 fBennegt; Mar.; 28 1944 products into said arc conducting passage in a 52450727 Atwood et a1. n Feb 1,1949 zone within said chute remote fromsaid zone of 5551993 Oppel et aL Jun 5; 1951 arcxnitiation. 2,570,610Taylor Oct. 9, 1951 DONALD E. WESTON.

FOREIGN PATENTS REFERENCES CITED 10 Numberk Country Date The followingreferences ae of record in the 403,068 Germany Sept. 26, 1924 le of thispatent: 649,237 Germany Aug. 21,1937

